Heretofore, the only way the characteristic curve for a particular color temperature could be obtained was using an experimental technique. That is to say, the film had to be exposed on a sensitometer with the lamp set at the color temperature desired. The film was then processed, densities read on a color densitometer and the curves plotted. The difficulty with the aforementioned technique was the problem involved in setting the color temperature in the first place and the tedious experimental procedures involved in performing the entire operation.